Rheostat



H. L. DODGE.

RHEOSTAT.

APPLICATION FILED MAR. I5, 1915.

1 1 95,660. Patented Aug. 22, 1916.

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HOMER L. DODGE, OF IOWA CITY, IOWA.

RHEOSTAT.

Specification of Letters Patent.

Patented Aug. 22, 1916.

Application filed March 15, 1915. Serial No. 14,537.

T all whom it may concern.

Be it known that I, HOMER L. Doncn, a citizen of the United States,residing at Iowa City, in the county of Johnson and State of Iowa, haveinvented a new and useful Rheostat, of which the following is aspecification.

This invention has reference to rheostats, and its object is to providea rheostat, as a unitary structure, whereby either the current or thevoltage of an electric circuit may be controlled at will.

In accordance with the present invention an adjustable rheostat isprovided, which rheostat may follow the lines of any suitable approvedform of rheostat, and in connection with such an instrument there isprovided the usual slider, or more than one slider where such anarrangement may be desirable.

At the full-resistance end of the rheostat a switch is provided, wherebythe rheostat may be connected across the circuit without disturbing theseries connection of the rheostat.

By this means the same instrument once connected in the circuit providesfor obtaining any desired current within the limits of the source, orany desired voltage within the limits of the source.

The invention is designed particularly for laboratory or class work, butis useful in other connections.

The invention will be best understood from a consideration of thefollowing detailed description, taken in connection with theaccompanying drawings forming a part of this specification, with thefurther understanding that while the drawings show a particular form ofthe invention, the latter is not confined to any strict conformity withthe showing of the drawings, but may be changed and modified so long assuch changes and modifications mark no material departure from thesalient features of the invention.

In the drawings :Figure 1 is a plan view with parts in diagramillustrating a rheostat constructed in accordance with the presentinvention. Figs. 2 to 6 are diagrams illustrating various adaptations ofthe invention.

Referring to the drawings there is shown in Fig. 1 a base board 1 whichmay represent any suitable support, and on this base board there is arheostat having a resistance element 2 conventionally illustrated indiagram. Capable of moving over the reslstance 2 which may be taken as.of the customary form of a coil of resistance wire,

part of the coil 2 along the length thereof to cut in or cut outresistance as may be desired.

One end of the resistance 2 is connected by a conductor 5 to a bindingpost 6 and alongside of the binding post 6 is another binding post 7.The two binding posts 6 and 7 may be conveniently located near one endof the base board 1, while near the other end of the base board are twoother binding posts 8 and 9, respectively. These binding posts aredesigned to receive conductors whereby the rheostat may be included in asuitable circuit. The binding posts 6 and 7 are designed to receive linewires 10, 11, respectively, and for convenience the word Line may bestamped or otherwise produced upon the base 1 adjacent to the bind ingposts 6 and 7.

The binding posts 8 and 9 are designed to receive conductors 12, 13,leading to the load, and adjacent to the binding posts 8 and 9 the wordLoad may be produced upon the base 1 for the convenience of theoperator.

The binding post 7 is connected by means of a conductor 14: to one sideof a fuse 15 which may be mounted on the base board 1, and the other endof the fuse is connected by a conductor 16 to the binding post 8, andthis conductor is also connected at an appropriate point to one side ofa switch 17, the other side of which switch is connected by a conductor18 to that end of the resistance 2 remote from the conductor 5. Theswitch 17 is provided with a switch arm 19 by means of which the switchmay be opened and closed at the will of the operator. While the switch17 is shown as of the familiar jack knife type, it will'be understoodthat the switch is to be taken as indicative of any suitable type ofelectric switch and the invention is not to be considered as confined toany particular construction of electric apparatus in such respects.

The

ductor guide bar 4 is connected by a conto the binding post 9.

Let it be assumed that the line conductors 10 and 11 are connected to asuitable source of current, and that the switch arm 19 is open.Furthermore, let it be considered that included in circuit with theconductors 12 and 13 is an appropriate load represented in Figs. 2 to 6as electric lamps 21, but which load is not Confined to any particulartype of translating device or devices.

if there be a certain voltage upon the line 10, 11, and the slider 3 beso located with respect to the resistance 2 that the latter is all cutout, the current delivered to the conductors 12 and 13 will be equal tothe voltage divided by the resistance of the load, as is, of course,well known, and the current may be reduced from the maximum thus stated,to any minimum within the range of the resistance 2 by moving the slider3 along the resistance to an appropriate point.

Again let it be assumed that there is a certain voltage on the line 10,11, and this may be the same voltage as first assumed. If the slider beat the beginning or zero end of the resistance and the switch arm 19 beclosed, the full voltage will be delivered to the conductors 12 and 13,and this also means full current as determined by the resistance of theload. If, now, the slider 3 be moved along the resistance 2 the currentwill divide, part passing by way of the slider 3 to the bar 1, andthence to the conductor 13, and part passing entirely through theresistance to the conductor 18, through the switch 17, and by way of theconductor 16, fuse 15 and conductor 14 to the other side of the mainline. The current which has passed to the load returns by conductor 12to the switch 17 and there joins the current flowingby way of conductor18 and switch arm 19 to the main 11. The result of this is that there isa drop of potential in the load conductors 12 and 13, and the voltagetherein will be approximately proportional to the ratio of the lengthsof resistance on opposite sides of the slider 3. In this manner even bythe employment of a single resistance and a single slider, the operatorhas at command any current or any voltage within wide limits, and thisis particularly valuable in the class room, or in the laboratory andunder certain circumstances may be of value elsewhere.

A particular feature of the present invention is that with oneinstrument connected up in the circuit and without the necessity ofmaking any changes whatever in the line connections, the operator may bythe simple expedient of opening or closing a switch and adjusting therheostat as needed, obtain any voltage from zero to maximum within therange of the instrument and any current from zero to maximum within therange of the instrument, and, of course, of the source of currentcharging the circuit.

In Figs. 2 to 6 twin rheostats comprising two resistances 2 aredisclosed. In Fig. 2 two sliders 3 are provided and one of theresistances 2 is connected across the line conductors 10, 11 by a switch17, while the other electrical conductors correspond to similar ones ofFig. 1 and are similarly indicated by reference numerals.

in Fig. 2 the slider bar 4 of one of the resistance coils 2 is connectedup to one end of the other resistance 2 and the slider bar 1 of thesecond resistance 2 is connected l a conductor 20 to the binding post asin Fig. 1. The arrangement of F differs from that of Fig. 2 in that theresistance coils 2 are connected up in series with the switch 17 inposition to couple directly to one of the slider bars 4-, while theother slider bar is connected as before by the conductor 20 to thebinding post 9.

The arrangement of Fig. 1 differs from that of the preceding figures inthat the two slider bars 1- are connected together in series, with theswitch 17 arranged to couple one of the resistance coils 2 across theline, while the other resistance 8 is connected by a conductor 20 to thebinding post 9. In the arrangement of Fig. 5 one of the resistances 2 isconnected in series with the slider bar 4 of the other resistance 2 andthe sec ond resistance 2 is connected by a conductor 2O to the bindingpost 9, as in Fig. a. The switch 17 is arranged to connect with theslider bar a of the first resistance 2 In Fig. 6 the two resistances 2are connected together in series by a conductor 20" with one resistance2 connected to the binding post 6 and the other resistance connected tothe binding post 9 by a conductor 20 There is provided a single sliderbar a with a slider 3 having two contacts for simul taneous engagementwith both coils 2*: The switch 17 is arranged to connect the conductor2O with the conductor 16 as before.

These examples are suflicient to illustrate the various ways in whichthe combined voltage and current rheostat of the present invention maybe arranged, and it is deemed unnecessary to multiply examples in orderto demonstrate the relatively wide range of variations of which thepresent invention is susceptible.

What is claimed is 1. A unitary current controlling device comprising abase or support, line and load receiving terminals on the base,resistance means on the base connected at one end to one of theterminals on the line side of the device, a direct connection on thebase from the other terminal on the line side to one of the terminals onthe load side of the device, a switch between the other end of theresistance means and the direct connection between the load and linesides of the device, and means connected to the other terminal on theload side of the device and adjustable with relation to the resistancemeans to include more or less resistance in circuit, the switch and thelast-named means being individually operable.

2. A combined voltage and current rheostat comprising a unitarystructure consisting of a base or support, a resistance and means forvarying it mounted on the base, means also on the base for making lineand load connections to the rheostat, and means on the base forconnecting the resistance at will across the means for making lineconnections, the means for varying the resistance and the last-namedmeans being independently operable, whereby variations in voltage may beobtained without disturbing the connections of the rheostat for currentregulation.

3. An instrument for obtaining variations in current or voltage at will,comprising a suitable base orsupport, a resistance and means for varyingit mounted thereon,

means for including the variable resistance in series between a sourceof current and the load, and means individual to the resistance forcutting said resistance into and out of shunt relation across thecircuit at will, whereby to provide for obtaining variations of voltagewhen the resistance is in such shunt relation.

4. A means for obtaining variable current or variable voltage at will,comprising a single instrument having a resistance and means for varyingit, said single instrument also including connecting devices forcoupling the variable resistance in a circuit to be controlled, otherconnecting devices for coupling the resistance to a source of supply,and a switch for connecting the variable resistance across the source ofsupply, the switch and the means for varying the resistance beingseparately operable.

In testimony that I claim the foregoing as my own, I have hereto afiixedmy signature in the presence of two witnesses.

HOMER L. DODGE.

Witnesses:

F. C. BROWN, P. T. MCNALLY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

